<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>

    <button>获取验证码</button>

    

    <script>

        var oBtn = document.querySelector('button') ;

        oBtn.onclick = function() {
            this.innerHTML = '10s倒计时';
            this.disabled = true ;
            var count = 10 ;
            var t = setInterval(function(){
                count-- ;
                oBtn.innerHTML = count + 's倒计时' ;
                if(count <= 0) {
                    clearInterval(t);
                    oBtn.innerHTML = '获取验证码' ;
                    oBtn.disabled = false ;
                }
            } , 500)
        }

    </script>
    
</body>
</html>